Charles e



'(No Model.)

C. E; SGRIBNER. TELEPHONE EXCHANGE APPARATUS.

No. 502,770. Patented Aug. 8, 1893.

III-lug in" .EIEEWHH lull!I UNITED STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OE CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERNELECTRIC COMPANY, OESAME PLACE.

TELEPHON E-EXCHANG E APPARATUS.

SPECIFICATION forming part of Letters Patent No. 502,770, dated August8, 1893.

Application filed October 15, 1888. Serial No. 288.139. (No model.)

To all whom it may concern:

Be it known that I, CHARLES E. ScRIBNER, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Telephone-ExchangeApparatus, (Case No. 170,) of which the following is a full, clear,concise, and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

In telephone exchanges it has been heretofore common to provide severalterminals or switches for each line and to group these terminals in suchmanner that each of several operators or switchmen may have room to workin making the connections and disconnections. This system is generallyknown as the multiple switchboard system. Each line has been providedwith a single annunciator and with as many switches or terminals asthere are switchboards. The individual annunciators of the differentlines are distributed among the different boards in such manner thateach operator may have as nearly as may be the same number ofsubscribers to answer. An operator at any board having received a callis enabled to connect the calling subscribers line with the line of anyother subscriber of the exchange, since each board is provided with adifferent terminal or switch for each of the telephone lines. Thissystem within certain limits hasbeen found the quickest and mostsatisfactory of any heretofore known or employed, since the diiterentoperators may do the entire work of connecting and disconnecting theparticular lines assigned their respective boards with one another orwith any other of the lines of the exchange. When, however, the numberof lines is very large and the possible connections of each subscriberthereby largely increased, it is found that the number of lines assignedto each board must be correspondingly decreased. Speaking generally, thegreater the number of lines v'in an exchange, the greater will be thenumber of calls made by each particular subscriber, and, consequently`the greater will be the amount of switchboard room required. Forexample, the lines of an exchange of a thousand subscribers might beconveniently handled on four switchboards, each operator being requiredto attend to the initial calls of two hundred and ifty subscribers, andthe whole number of switches or terminals in the exchange required beingfour thousand. In an exchange having three thousand subscribers, notmore than two hundred lines should be assigned to one switchboard; hencethe number of switchboards required would be fteen and the number ofterminals would be forty ive thousand. Now, if instead of assigning twohundred to each board, two hundred and fifty should be assigned to eachboard, only twelve boards would be required and the whole number ofterminals in the exchange would be thirty six thousand. It thus appearsthat the cost of providing switchboard room increases in a much greaterratio than the actual ratio of increase of subscribers and that the puremultiple switchboard system on this account becomes too expensive afteran exchange becomes very large.

My invention herein relates to multiple switchboard systems in whichmetallic circuits are employed, and its object is to reduce the numberof switches or terminals heretofore required in such systems in orderthat it may be commercially practicable to run from six to ten thousandtelephone lines into the same oc'e and provide ready means forconnecting any two of these lines together on any one of severalswitchboards.

I have deemed it unnecessary to describe or illustrate any test systemor means for determining'at one board whether a line called for is inuse or connected at any other of the boards, since there are varioussystems of doing this work which are well known and which might bereadily applied by any one skilled inthe art.`

Myinvention consistsin dividingtheswitchboards into two groups andproviding aswitch or terminal for each of, say, halfthe lines on eachboard of one of the groups, and a terminal` or switch for each of theother halfof the lines upon each of the boards of the other group andincluding in each .limb of each metallicV circuit a different individualannunciator, the two annunciators of each line or metallic circuit beingplaced each on a board of a different group of the boards, withsignaling apparatus at the diierent subscribers IOC stations for sendingcurrent over either limb of the metallic circuit to throw down theshutter of one division or other division of the exchange at the will ofthe subscriber, the lines of one division being provided each with ananswering spring jack near the annunciator of the line upon a board ofthe other division. The subscribers must be instructed that theterminals of lines below a certain number are of one division, asdivision A, and that the terminals of the lines above that number arefound in the other division. Thus, a subscriber looking at his directorywould at once know to which division of the exchange a subscriber of agiven number belonged, and therefore would send current over one limb orthe other ot' his metallic circuit to thrown down the shutter which isupon a board of the division of the exchange to which the wantedsubscriber belongs.

My invention is illustrated in the accompanying drawings, in which-Figure l is a diagram illustrative of a telephone exchange divided intwo divisions,two multiple boards being shown in section in eachdivision with the circuits of four 'telephone lines connected therewithin accordance with my invention, the circuit of one line being shownindetail. Fig. 2 isa detailed View of the preferable form of springjackswitch.

Switchboards l and 2, we will say, belong to division A, whileswitchboards 3 and 4belong to division B. The subscribers stations 1 and2 are connected each with a diiterent springjack switch or terminal oneach of the boards of division A and with a springjack switch on oneboard only of division B. Stations and 4c are connected each with adiiterent springjack on each of the switchboards of division B and alsoeach with a springjack switch or terminal upon one board only ofdivision A.

I will now describe and trace the circuit of station 1 in detail, itbeing understood that the other subscribers stations of the exchange areprovided with the same apparatus and connected with the central otice inthe same manner. Beginning at ground near annunciator ci of board 2, thecircuit of station l maybe traced through said annunciator ci by limb bthrough the lower spring and contact of answering switch con board 3;thence through the lower contact and spring of switch (Z upon board 2;thence through the lower spring and contact of switch or terminal c uponboard l; thence to key f at station l; thence to the telephone switch g;thence through the generator and bell to key h; thence by limb t'through the upper spring and contact of switch e; thence through theupper spring and contact of switch d upon board 2 of division A; thencethrough the upper spring and contact of springjack switch c upon board 3of division B; thence through the annunciator 7o on said board 3 andthence to ground. By means of key h, limb b may be closed to ground atstation l to bring .the generator into circuit and thus, by turning thegenerator, current may be sent over limb b to operateaiinunciator a uponboard 2 of division A. By depressing keyf, at station l, limb t' may beclosed to ground at said station l and byturning the generator, currentmay be sent over line 'L' to throw down the shutter 7s upon board 3 ofdivision B ot the exchange. Thuseach subscriber is provided with ametallic circuit. One limb o f the metallic circuit, as limb b, isprovided with an annunciator upon a board of divisionA, while the otherlimbi' of the metallic circuit is provided with an annunciator llc upona board of division B of the exchange.

Suppose subscriber l wishes a connection with another subscriber of theexchange. As soon as he looks up the number of the subscriber wanted, hewill know to which division of the exchange the subscriber wantedbelongs. W'e will suppose that the subscriber wanted is the one atstation 2. Subscriber l will know that the subscriber wanted belongs todivision A. He will therefore depress key 7i and send current overbranch b whose 1ndividual annunciator a is upon a board of the divisionor group A. rlhus, having thrown down the shutter a, the operator atboard2 is notified of the call, and proceeds to answer it and make theconnections in the usual manner. We will now suppose that subscriber lwishes to talk with subscriber of station He will now depress key f andoperate his generator, sending current over limb t through annunciator kupon a board of the group or division B to which subscriber 4: belongs.The operator at board 3 will thereupon proceed to make the connectionsbetween the answering springjack c of subscriber 1 and the springj ack Zof subscriber l upon said board 3 in the usual manner. Thus by my systemeach subscriber is required to have a springjack switch or terminal uponeach of the boards of one division and one springjack switch additionalupon some one of the boards of the other division in connection with anadditional individual annunciator. The usual keyboard apparatus isprovided at each board, as illustrated at board 4.

Having thus described my invention, I claim as new and desire to secureby Letters Patentum l. A metallic circuit extending from a subscribersstation to a telephone exchange central office, in combination withmultiple switchboards in groups or divisions, both limbs of saidmetallic circuit extending through and being connected with a differentswitch upon each of the boards of one division and with a switch uponone board of the other division, one limb of said circuit containing anindividual annunciator upon a board of one division and the other limbof said circuit containing an individual annunciator on a board of theother division, and signaling apparatus; whereby either individ- IOO IIO

1o adapted to be separated by the insertion of a plug in any springjack,whereby both annuncators are disconnected when connection 1s made to theline, substantially as descrlbed. In witness whereof I hereuntosubscribe my name this 28th day of July, A. D. 1888.

CHARLES E. SCRIBNER.

Witnesses:

CHAS. G. HAWLEY, CHAS. C. WooDwoRTH.

